* {
  box-sizing: border-box;
}
body {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  overflow: hidden;
  margin: 0;
}
.bg {
  background: url('http://img.mp.sohu.com/upload/20170807/d8d3c433aaf04eb0965bf2086441213d_th.png') no-repeat center center/cover;
  position: absolute;
  top: -30px;
  left: -30px;
  /* 动态计算宽度和高度 */
  width: calc(100vw + 60px);
  height: calc(100vh + 60px);
  z-index: -1;
  /* // 滤镜  可以写模糊效果 */
  filter: blur(0px);
}
.loading-text {
  font-size: 50px;
  color: aquamarine;
}